[Study of the evolution of some monocytic parameters and neuroendocrine function tests in depressed patients]

The development, evaluation and use of biological markers is extremely important in Psychiatry. However, with certain exceptions, truly sensitive and specific markers have not still emerged. Several studies have reported immune cellular and humoral dysfunction during depression. We specifically focused on the study of the monocyte because it has a key role in the activation of the immune response. We also investigated the relationship between the immune apparatus and the hypothalamic-pituitary activity in depressed patients.

We used a longitudinal design and assessed monocyte parameters (HLA-DR, CD 35, vimentin filaments and phagocytosis index) and neuroendocrine tests (DST and TRH-test) at intake (pretreatment phase: phase I) and at follow-up (post-treatment phase: phase II) in 49 depressed patients according to Research Diagnostic Criteria (RDC). The mean follow-up interval was 12.2 +/- 2 weeks. The severity of illness was measured by means of the Hamilton Depression Rating Scale (HDRS).

Seventy per cent of patients showed a pretreatment marked monocyte dysfunction (82.5% had at least one parameter altered). After treatment, alterations in immunological variables were significantly associated (p < 0.05) with depression scores higher than 15). We did not find any significant association between the severity of depressive symptoms and the results of the neuroendocrine tests. The combined use of both immunological and neuroendocrine tests did not add sensitivity to the immunological identification of depressed patients. Before and after treatment the immunoreactive vimentin filaments significantly increased (p < 0.01) after incubation of monocyte with naloxone. There was a significant correlation (p < 0.05) between the immune parameters studied in both phases of the study.

The findings indicate that the monocyte dysfunction is temporally associated with the state of depression and lead us to consider the role of the monocyte parameters as sensitive depressive state markers, while the combined use of both neuroendocrine and immunological tests in current clinical practice would be debatable. On the other hand, as the cytoskeletal dysfunction was reversed with naloxone, our findings underline previous reports suggesting that an increased opioid activity could mediate monocyte dysfunction.